title: The μPIVOT: an integrated particle image velocimeter and optical tweezers instrument for microenvironment investigations.
abstract: A novel instrument to manipulate and characterize the mechanical environment in and around microscale objects in a fluidic environment has been developed by integrating two laser-based techniques: micron-resolution particle image velocimetry (μPIV) and optical tweezers (OT). This instrument, the μPIVOT, enables a new realm of microscale studies, yet still maintains the individual capabilities of each optical technique. This was demonstrated with individual measurements of optical trap stiffness (∼70 pN μm(-1) for a 20 μm polystyrene sphere and a linear relationship between trap stiffness and laser power) and fluid velocities within 436 nm of a microchannel wall. The integrated device was validated by comparing computational flow predictions to the measured velocity profile around a trapped particle in either a uniform flow or an imposed, gravity-driven microchannel flow (R(2) = 0.988, RMS error = 13.04 μm s(-1)). Interaction between both techniques is shown to be negligible for 15 μm to 35 μm diameter trapped particles subjected to fluid velocities from 50 μm s(-1) to 500 μm s(-1) even at the highest laser power (1.45 W). The integrated techniques will provide a unique perspective toward understanding microscale phenomena including single-cell biomechanics, non-Newtonian fluid mechanics and single particle or particle-particle hydrodynamics.
authors.affiliation: Department of Mechanical & Materials Engineering, Portland State University, PO Box 751, Portland, OR 97207-0751, USA.
authors.forename: N
authors.initials: N
authors.lastname: Nève
authors.forename: J K
authors.initials: JK
authors.lastname: Lingwood
authors.forename: J
authors.initials: J
authors.lastname: Zimmerman
authors.forename: S S
authors.initials: SS
authors.lastname: Kohles
authors.forename: D C
authors.initials: DC
authors.lastname: Tretheway